496 PROCEEDINGS OF THE NATIONAL MUSEUM vol. no 



Female. — Length 10 mm. Black with yellow markings; punctation 

 and pubescence average. 



Head subequal in width to the thorax; black except frontal eye 

 patches, clypeal process, base of mandibles, small spot above the 

 process, and small spot back of the eyes, all of which are yellow; 

 clypeal border extended from the medial lobe, showing broad, blunt 

 denticles at the lateral angles of the extension and a much smaller 

 medial denticle; clypeal process of the inverted scoop type but 

 subequal in width and length, deeply emarginate with the lateral 

 points very acute; mandibles with three denticles, the most apical 

 one larger and separated from the two basal denticles, which are 

 joined at their bases and subequal in size; antennae dark, normal in 

 form. 



Thorax black except for two widely separated spots on the prono- 

 tum, the metanotum, and small patch on the tegulae, all of which 

 are yellow; tegulae low and smooth; enclosure rugose, with the 

 ridges extending longitudinally; mesosternal tubercle absent; legs 

 dark to or near the apical end of the femora of all legs, beyond 

 which they are mostly yellow; wings subhyaline but clouded in the 

 apical area; stigma medium dark; pygidium with the sides converging 

 to a rounded apical end. 



Abdomen with subequal bands on all terga 1 to 5 except that 

 on tergum 1 it is divided at the meson; venter immaculate; pygidium 

 with sides slightly converging to a rounded apical end. 



Male. — The subspecies C. nigrescens arelate Banks is structurally 

 close to C. nigrescens nigrescens F. Smith except for the lighter mark- 

 ings, which are yellow, the lateral clypeal denticles, which are more 

 prominent, and the usual absence of light markings on the tergum 

 and the venter of the former. 



The female of C. nigrescens arelate Banks is very near in form and 

 color to the female of C. nigrescens nigrescens F. Smith, from which 

 the former is separated by the form of its clypeal process and the 

 very acute lateral points of its process. The latter is inclined to have 

 the markings somewhat creamy yellow in the typical form found in 

 the northeast, while C. nigrescens arelate Banks has bright yellow 

 markings. 



Types. — The type female of C. arelate Banks, from Great Falls, 

 Va., June 20, is at the Museum of Comparative Zoology, Harvard, 

 no. 13779. The type male of C. nigritulus Banks, from Golden, 

 N.Y., July 3 (M. G. Van Duzee), is at the Museum of Comparative 

 Zoology, Harvard, no. 13782. The type male of C. crawiordi Brimley, 

 from Raleigh, N.G., July 1928, is in the collection of the North 

 Carolina State Department of Agriculture, Raleigh, N.C. 



